• update Gradle to the last patch release within the same major version you currently are
• update plugins to the latest versions compatible with your Gradle version
• execute all relevant tasks and fix all deprecation warnings
• update Gradle to the last patch release within the next major version, considering release notes and upgrade guide in the usermanual
• update plugins to the latest versions compatible with your Gradle version
• rinse-and-repeat until you are at the version you want to end up on
This usually makes for a pretty smooth upgrade experience